/*
 * Copyright (C) 2010-2021 Sebastiano Vigna
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package it.unimi.dsi.fastutil;

import java.util.Iterator;
import java.util.ListIterator;

/** A list iterator over a {@link BigList}.
 *
 * <p>This kind of iterator is essentially a {@link ListIterator} with long indices.
 *
 * @see Iterator
 * @see ListIterator
 */

public interface BigListIterator<K> extends BidirectionalIterator<K> {

	/** Returns the index of the element that would be returned by a subsequent call to next.
	 * (Returns list size if the list iterator is at the end of the list.)
	 *
	 * @return the index of the element that would be returned by a subsequent call to next, or list
	 * size if list iterator is at end of list.
	 * @see ListIterator#nextIndex()
	 */

	long nextIndex();

	/** Returns the index of the element that would be returned by a subsequent call to previous.
	 * (Returns -1 if the list iterator is at the beginning of the list.)
	 *
	 * @return the index of the element that would be returned by a subsequent call to previous, or
	 * -1 if list iterator is at beginning of list.
	 * @see ListIterator#previousIndex()
	 */

	long previousIndex();

	/**
	 * Replaces the last element returned by {@link #next} or
	 * {@link #previous} with the specified element (optional operation).
	 *
	 * <p>This default implemention just throws an {@link UnsupportedOperationException}.
	 *
	 * @param e an element.
	 * @see ListIterator#set(Object)
	 */
	default void set(final K e) {
			throw new UnsupportedOperationException();
	}

	/**
	 * Inserts the specified element into the list (optional operation).
	 *
	 * <p>This default implemention just throws an {@link UnsupportedOperationException}.
	 *
	 * @param e an element.
	 * @see ListIterator#add(Object)
	 */
	default void add(final K e) {
		throw new UnsupportedOperationException();
	}
}
